Liquid level sensitive apparatus



1944- H. J. OSTERMANN ETAL 2,354,964

LIQUID LEVEL SENSITIVE APPARATUS Filed May a. 1959 I IINVENTOR.

E I flansdwfemam and meadow/4. Cohen 6 ATTORNEYS.

tion;

Patented Aug. 1, 1944 "UNITED STATES. PATENT OFFiCE ZM! uoum mm.smsrrrva mana'ros HansLOItermannandTheodoI-eLCohen,

IlL, assignon, bymeane assignments.

lnstrumentscomnm,

Illinois co corporation of Ohito Chicago, 111., a

Application May 8, 1989, Serial No. 271,865 9 Claim!- icl. 73-804) Thisinvention relates to liquid level sensitive apparatus in general andmore particularly to responsive to variations in liquid level andperforming certain useful functions, such as recording and indicatingliquid level changes, in accordance with such variations.

Other and further objects of this invention will be more apparenthereinafter from an examina tion of the specification and claims inconjunction with the accompanying drawing wherein: I

Fig. 1 represents a schematic view of a particular embodiment of theinvention showing a liquid level sensitive apparatus responsive tovariations of liquid level in a container such as a boiler, storage tanketc. and for performing various useful functions in accordance with suchvariations; 1 x

Fig. 2 represents a similar view of a modifica- Fig. 3 isa detailfragmentary sectional view of a modified form of liquid level sensitiveinductance device capable of use in either of the circuits of Figs. 1and 2 in lieu of the liquid level sensitive capacity device showntherein.

Referringto Fig. 1, reference character i designates theliquid input toa container 1 which the capacity of the condenser formed by theconductors I and t.

The conductors 1 and l are connected to the opposite sides,respectively, of a grid tank inductance" which together with thecondenser formed by asid conductors constitutes said grid tank. Thisgrid tank may begrounded as at H and has one side connected through agrid resistor II and a grid condenser I to the'grid ii of an oscillatortube II and the other side connected to the filament I of said tube. Afilament heating source I! is provided for filament ii. The oscillatortube has a plate ll connected to one side of a plate tank comprising aplate tank inductance II and a variable plate capacity 25. The otherside of the plate tank is connected to a plate power source 23 throughan isolatin choke coil 22 and a neutral position relay 24.

A coupling or by-pass condenser 20 is connected between the filament anda point between the choke'coil i2 and the plate tank ll-Ii.

The tank ii-Ii in. the plate circuit is tuned to predetermined resonancewith the grid tank 1+, when the level-[is at the chosen initial point;the tuning being so chosen that the plate current through the relay II,at such initial point, is at such level as to keep the relay contact I!in the neutral position shown. Should a liquid level change occur, thecapacity change thereby produced will change the tuning of the grid tank1l-|2 deresonating or reresonatr' ing same depending upon direction ofliquid level change together with the plate tank 2 I-II; causing achange in plate current throughQrelay 24 which thereupon makes contact88 or 31 depending upon whether the liquid level has increased ordecreased at 4. Thus the plate current will act upon relay 24corresponding to variations in liquid level from said initial point tocorrespondinglycontrol other means hereinafter described including meansfor restoring the may be a boiler, storage tank or'the like. The

predetermined resonance of the circuit.

The armature and contact plate 35 of the relay 24 is connected,preferably through a flexible conductor I8, and through an anti-huntingdevice 32-43-444, tobe more particularly described hereinafter, to oneterminal of a source of current ii for a reversing motor 30. The motorSI is of a suitable type provided with a pair of field coils (not shown)having terminals 300 and 800, respectively, and a common centralterminal 30b. Contact ll leads to terminal 300 and contact 31 leads toterminal 30c. Terminal Iiib leads to the other terminal of source 3i.

The grid-and plate tanks being predeterminedly resonated with respect toeach other to such extent as to provide an intermediate plate currentlevel when the li'quidlevel l is at the chosen initial point, armature"will assume a neutral position under such circumstances. When theliquid level is loweredfrom such point, the reduction in capacitythereby across the grid tank detunlng the latter from the aforesaidpredetermined resonant position with the plate tank and causing a risein plate current above the aforesaid intermediate level, the armature 35will contact with contact 33 to drive motor 35 in one direction; andwhen the liquid level is raised, armature 35 will contact with contact31 by virtue of lowering of plate current below said intermediate levelto drive said motor in the opposite direction.

The manner and means by which this motor 35, controlled as previouslydescribed, acts in turn to restore the tuning and balance of theoscillating circuit and operate other means, including liquid levelindicating and recording devices, will now be described.

The motor 35 is provided with a pulley 23 and drive 25 therefrom, whichmay take any suitable form, connected to an indicator shaft 25b which inturn is drivingly connected by means of a suitable drive 21 to the shaftof variable plate tank condenser 25. The amount and direction that theindicator shaft 251) and plate tank condenser shaft are operated dependsupon the degree and direction of rotation of motor 35. When tankcondenser 25 has been thus adjusted sumciently to restore thepredetermined resonant condition of the oscillating circuit, a pointer25a on shaft 25b will indicate the new liquid level on a dial 25calibrated in liquid column height and the motor 35 will stop, becausethe relay 24 will be restored to neutral position. Thereafter anydeviation in liquid level from the new liquid level will similarlyunbalance the oscillating circuit with resultant restoration andindication in the same manner.

The reversing motor 35 may be coupled to a recording mechanism and otherdevices either in the manner shown in our copending application Ser. No.267,326, filed April 11, 1939, for Liquid level sensitive apparatus, orby means of a coupling or drive 23a, and such liquid level recordingmechanism and safety devices operable in accordance with liquid levelchanges may take the same form as shown in said copending-application.

The anti-hunting device, previously referred to, may take any suitableform and be placed in any suitable part of the electrical circuit ormechanism but is here shown comprising a cam 32 on a suitably timeddrive shaft 33. An interrupter having stud 35a and contact 34 isoperated at timed intervals by the cam 32 and introduces a time lagwhich prevents recurrent cycling or hunting in the apparatus as a whole.

Referring to Fig. 2, there is here shown a somewhat similar form of theinvention, except that here the liquid level sensitive device, adaptedtounbalance the oscillating circuit in accordance with the liquid levelchanges, is of the immersion type and also, in this embodiment, theoscillating circuit itself is not restored to balance by the reversingmotor. Instead a differential relay is used in the plate circuit and thechange in plate current from predetermined intermediate level due toliquid level changes is counteracted and neutralized during therestoration operation by the reversing motor whereby the eifect of theunbalance of the plate current on the relay is neutralized and the relayin rebalanced to stop the reversing motor and the indicator pointer atthe new level.-

The oscillating circuit, in this embodiment, is adapted to be unbalancedby the liquid level sensitive device in accordance with liquid level andit will remain unbalanced unless and until that point is resumed and theliquid level sensitive device in response to such resumption in levelhas effected such rebalance. But the relay itself is rebalanced aftereach change in liquid level as will be more particularly describedhereinafter.

More particularly there is shown a container 42 with liquid 4| thereinat a variable level 44. A glass or otherwise non-metallic hollow member45 depends from a non-metallic annular supporting fitting 41 mounted inan opening in the top of container 42. The hollow member 45 is sealed atits lower end to exclude liquid and is partly immersed therein. It isshaped to provide a pair of opposite chambers for supporting therein apair of vertically extending and horizontally spaced capacity elements44 and 43. Here likewise the water in the container acts as a dielectricand the elements 43 and 44 act as plates of a condenser. These elements43 and 44 act substantially the same as elements 1 and 5 of the previousembodiment and are likewise connected,

- respectively, to opposite sides of the grid tank |2 in said previousembodiment.

inductance 33, corresponding to the inductance Parts 48, 49, 55, 5|, 52,53, 54, 55, 55, 51, 55, 59, and 60 are similar to corresponding partsl3, l4, I5, l5, I5, l1, I5, 20, 23, 2|, 25, 22, 24, respectively, in theprevious embodiment, except that here the plate tank condenser 55 is notmotor driven and the relay 50 is differentially wound with an additionalcoil 5| thereon adapted when energized to counteract and neutralize theeifect of the plate current in the first coil thereof. Parts 55, 55a,59, III, II, 12, 13, 14,15, 15, I1, 15, 19,55, 53, 54, 55, 55, and 51are similar to corresponding parts 25b, 25a, 25, 26, 25, 30, 35a, 30c,30b, 35, 35, 35, 31, 25a, 32, 33, 38a, 54 and 3|, respectively, exceptthat the indicator shaft 58 has no driving connection to the plate tankcondenser. Instead reversing motor 12 is suitably connected to drive arotatable contact member 55 of a rheostat to vary the amount ofresistance 54 in circuit with the counter-winding 5| of the differentialplate relay. A source of current 52 is provided for such circuit andalso an ammeter 53 calibrated in liquid column height. A recordingapparatus 52 similar to that previously referred to in the formerembodiment and in our copendingapplication aforesaid together withsafety devices as also shown in said copending application may be drivenfrom said drive 50 from the reversing motor.

The amount and direction.that the rheostat finger 55 must be moved bythe reversing motor to suiliciently energize or deenergize thecounteracting coil 5| in the differential relay to balance the platecurrent in coil 55 to cause it to resume the neutral position shown andstop said motor after a liquid level change has occured is a measure ofthe extent of said change and indicative of the new level. Thus thefinger 55 may itself be an indicating pointer and the ammeter 53 anindicator both showing liquid level changes as well as indicator55-55a-l0. In this embodiment, when a liquid level change occurs, thecapacity change thereby produced across the grid tank will change thetuning thereof deresonatchanges from the predetermined initial point,

ing or reresonating, as the case may be, same together with the platetank; causing av corresponding change in plate current through relaycoil 55 which thereupon makes contact 15 or I5 depending upon whetherthe liquid level has increased or decreased at 45.

'reactance or both.

Referring particularly to Fig. 3, there is here shown a modified form ofliquid level sensitive inductance device of the immersion type adaptedto be inserted in liquid to cooperate with the previous circuits in lieuof the liquid level sensitive capacity devices shown therein. Herein isshown a hollow immersed member 80 sealed at its lower end to exclude theliquid 92 in the container (not shown). This member corresponds tomember 45 in the previous embodiment and likewise is depending from anon-metallic fittin 88. In this case, however, a vertically arrangedinductance coil9l is mounted in the hollow immersion member instead ofcapacity members such as 43-44. Inductor leads 8! are connected to theterminals, including lower terminal 83, oi. the coil 9|. When thisliquid level sensitive inductance device, including member 90 with coil9| therein, is used instead of the device, including member withcapacity members 43- therein, in either circuit previously described,

said coil 9| may take the place of either of the following inductances:39, I2, 2|, or 51 to unbalance the respective circuits in accordancewith liquid level changes in the same manner as the liquid levelsensitive capacity devices in said circuits so function.

The oscillator circuits may take a variety of forms and the liquid levelsensitive inductance and/or capacity devices shown may be placed inother parts of said circuits than across the grid tanks as shown.

Where the term electrical reactive is used in the appended claims it isintended to cover generically either capacitive reactance, inductive Weare aware that many changes may be made and details varied withoutdeparting from the principles of our invention and we therefor do notwish to be limited to the details shown or described.

We claim:

1. In an apparatus 01 thecharacter described, the combination of aliquid container, a pair of spaced metallic members out of directelectrical contact with the liquid in the container and extending asubstatnial distance above and below a predetermined level of the liquidin such position that change in said level will correspondingly vary thecapacity between said members, an electronic oscillator connected tosaid members for detuning thereby and means, controlled in turn by saidoscillator, for automatically returning the oscillator and indicatingthe new liquid level.

2. In an apparatus of the character described, liquid level sensitivemeans, an electrical circuit adapted to be unbalanced thereby. a relayin said circuit and control means responsive to said relay forautomatically restoring the same independently of such unbalance of thecircuit.

\ 3. In an apparatus of thecharacter described, liquid level sensitivemeans, an electrical circuit adapted to be unbalanced thereby, adifferential relay having counteractingcoils, one coil in said circuitand a control circuit containing the other coil and controlled by saidfirst circuit for automatically rebalancing said relay.

4. In an apparatus of the character described, liquid level sensitivemeans, an electrical circuit adapted to be unbalanced thereby, a relayin said circuit and means responsive to said relay for automaticallyrestoring the same independently oi uch unbalance oi the circuit and forindicating liquid level change.

5. In an apparatus of the character described, liquid level sensitivemeans, an electrical circuit adapted to be unbalanced thereby, a relayin said circuit and means responsive to said relay for automaticallyrestoring the same independently of such unbalance oi the circuit andfor recording liquid level change.

6. In an apparatus or thecharacter described, liquid level sensitivevariable electrical reactive means, an electrical circuit adapted to beunbalanced thereby, a relay in said circuit and means responsive to saidrelay for automatically restoring the same independently or suchunbalance of the circuit.

7.. In an apparatus of the character described, liquid level sensitivevariable electrical reactive means, an electrical circuit adapted to beunbalanced thereby, a diflerential relay having counteracting coils, onecoil in said circuit, and a control circuit containing another coil andcontrolled by said first circuit for automatically rebaiancins saidrelay.

8. In an apparatus or the character described. liquid level sensitivevariable electrical reactive means, an electrical circuit adapted to beunbalanced thereby, a relay in said circuit. a second circuit adapted tobe controlled by said relay and including a prime mover and a thirdcircuit controlled by said prime for automatically counteracting thedegree or unbalance or said relay.

9. Inanapparatusotthecharacterdescribed, liquid level sensitive means,an electrical circuit adapted to be unbalanced thereby, a diflerentialrelay havingapairoicounteractingmoneccilinsaidcircuitasecondcimritoontainingthe other coilandcontrolledbysaidilrstcircuitior automatically rebalancing said relayand means responsive to the second circuit tor indicating liquid levelchanges.

J. OW. A. com.

